Dimensional Stability of LDPE Foams: Modeling and Experiments

Yang, Chi-Tai; Lee, Kevin Lujan; Lee, S. T.

doi:10.1177/0021955x02038002243

Cited by 18 publications

(12 citation statements)

References 2 publications

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“…The shrinking behavior always happened to the soft foams with low modulus or low stiffness. 23 It was mainly related to the displacement of the gas inside cells. Just after foaming, the cells of the TPU foams were supported by CO 2 gas of higher pressure than the ambient pressure.…”

Section: Resultsmentioning

confidence: 99%

Microcellular thermoplastic polyurethanes and their flexible properties prepared by mold foaming process with supercritical CO₂

Jiang

Zhao

Feng

et al. 2019

Journal of Cellular Plastics

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A mold foaming process for preparing thermoplastic polyurethane foam sheets was proposed and realized in pilot scale hot-press machine based on the mechanism of solid-state polymer foaming. Thermoplastic polyurethane microcellular sheets with volume expansion ratios of 2.2-7.0 were prepared by adjusting foaming temperature of 95-120 C at the fixed CO 2 pressure of 12 MPa with natural post-curing. The good foam dimensional stability and the uniform cell morphology of these thermoplastic polyurethane foams suggested that the mold foaming of thermoplastic polyurethane sheet was feasible. Regardless of volume expansion ratio, a linear shrinkage of 17-19% occurred to all thermoplastic polyurethane foams after post-curing. The flexible properties of these post-cured thermoplastic polyurethane foams, such as hardness, rebound resilience, compression set, and dynamic shock absorption, were investigated. The test results indicated that these thermoplastic polyurethane foams were excellent flexible materials.

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Section: Resultsmentioning

confidence: 99%

Microcellular thermoplastic polyurethanes and their flexible properties prepared by mold foaming process with supercritical CO₂

Jiang

Zhao

Feng

et al. 2019

Journal of Cellular Plastics

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“…Obviously, these results are in agreement with the variation in strand diameter evidenced in Figure 10. Several papers have already treated this shrinkage issue for lowdensity foams, especially in the case of low density polyethylene foams (31) and PCL blown with CO 2 (32) . Works conducted over the past decade have shown that the contraction of the cellular structure is caused by the buildup of a negative pressure inside the cell cavities.…”

Section: Dimensional Stability Of Low Density Pla Foamsmentioning

confidence: 99%

Extrusion Foaming of Poly(Lactic acid) Blown with CO₂: Toward 100% Green Material

2007

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“…The gas diffusion process in closed cell foams is described for PE foams by Yang, Pilon and Briscoe [24,15,3]. Pilon et al [15] described the effective diffusion coefficient through the foam as a product of the geometric factor and the gas diffusion coefficient through the foam membrane.…”

Section: Aging-dimensional Stabilitymentioning

confidence: 99%

“…8, it is shown schematically that the phenomenon of the so-called breathing foam cells due to diffusion process of blowing agent and molecules of ambient air as described in the literature. Briscoe and Yang [24,3] described the mass diffusion as a function of the blowing agent and the air counter diffusion, but did not take the temperature dependency into account. Fig.…”

Section: Aging-dimensional Stabilitymentioning

confidence: 99%

Long-term durability of CFRP foam core sandwich structures

et al. 2011

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The work presented in this article is directed towards the application of CFRP foam core sandwich structures as primary structures in commercial aviation. With closed cell rigid foams, it is possible to produce comparatively low priced high-integral sandwich components having a complex geometry in terms of a curved and a variable lateral cut. Sandwich structures are offering a good bending stiffness and strength to weight ratio. Thus, they are suited for using in structures which are at risk to fail by buckling (Herrmann et al. Sandwich structures 7: advancing with sandwich structures and materials, 2005). The investigations are focused on a CFRP sandwich structure with polymethacrylimide (PMI) foam core, named ROHACELL Ò RIST. Besides good structural stability at thermal conditions, the foam is characterized by a good strength and stiffness to weight ratio (Seibert, Reinforced Plast 50(1): [44][45][46][47][48] 2006). Primary structures in aircraft applications are exposed to a superposition of in-service loads and environmental conditions. The typical working loads in combination with environmental conditions were investigated. The structure needs a sizing with respect to large temperature changes and influences of humidity. Thus, the time, temperature, and moisture dependency of the mechanical behavior were studied for the single components of the structure and for the composite itself. Therefore, Finite Element Models on macroscopic level were built with reference to the experiments. For each in-service case, the residual stresses arising during manufacturing have to be regarded and quantified (John et al. ECCM14, 2010). During manufacturing, the sandwich structure is cured at 180°C. Due to the different stiffnesses and coefficients of thermal expansion of the foam and the CFRP face sheets, residual stresses are induced by cooling down to service temperature. Among others, some tests were made at laterally closed CFRP sandwich structures with a storage time up to half a year at certain climate conditions. The aging process is not only controlled by external conditions, but also by a rearrangement of molecules, for example, the relaxation behavior of the PMI foam (Gutwinski et al. Verbundwerkstoffe. Wiley, Weinheim, 2009). Another question of the long-term behavior of the CFRP foam core sandwich structure is the characteristic of delamination of the face sheets from the inner core after an impact has occurred. To describe the crack growth behavior of the sandwich structure fracture mechanical principles can be used estimating the damage tolerance. Sandwich specimens with initial damage were loaded up to 3 million mechanical load cycles.

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Dimensional Stability of LDPE Foams: Modeling and Experiments

Cited by 18 publications

References 2 publications

Microcellular thermoplastic polyurethanes and their flexible properties prepared by mold foaming process with supercritical CO₂

Microcellular thermoplastic polyurethanes and their flexible properties prepared by mold foaming process with supercritical CO₂

Extrusion Foaming of Poly(Lactic acid) Blown with CO₂: Toward 100% Green Material

Long-term durability of CFRP foam core sandwich structures

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Dimensional Stability of LDPE Foams: Modeling and Experiments

Cited by 18 publications

References 2 publications

Microcellular thermoplastic polyurethanes and their flexible properties prepared by mold foaming process with supercritical CO2

Microcellular thermoplastic polyurethanes and their flexible properties prepared by mold foaming process with supercritical CO2

Extrusion Foaming of Poly(Lactic acid) Blown with CO2: Toward 100% Green Material

Long-term durability of CFRP foam core sandwich structures

Contact Info

Product

Resources

About

Microcellular thermoplastic polyurethanes and their flexible properties prepared by mold foaming process with supercritical CO₂

Microcellular thermoplastic polyurethanes and their flexible properties prepared by mold foaming process with supercritical CO₂

Extrusion Foaming of Poly(Lactic acid) Blown with CO₂: Toward 100% Green Material